Building a Clock – From Design to Not-Quite-Working Prototype

Most of the projects I post here are in some state of functionality, but this mechanical clock I’ve been working on is a very large project, so here’s where I am in the build.  I’ve taken several videos of my progress, but I thought I’d start with the escapement first, since to me it’s the most interesting single mechanism in a clock.

As noted, I really thought it would be the most difficult part, but after laying everything out on the AutoCAD-like Draftsight (my review for Windows or Ubuntu), it turned out pretty well.  The difficult part is turning out to be the gears.

Tmechanical-clock-cadhe original clock CAD design, as seen in the sketch to the right, has the gears setup to act as their own hands.  The second “hand” is to be the purple-ish gear to the right.  This is then gear-reduced by a factor of 3600 (seconds per hour) to make the top-middle green gear the minute “hand.”  The leftmost gear is then geared by a factor of 12 to act as the hour hand.  In theory this should be really easy.

In reality though, there are still a few issues to work out.  I’ll let the next videos do most of the talking, but they mostly stem from the pulley and escapement pendulum interfering with each other, and my fear of the pulley being too far from the base board.  I also seriously oversimplified the gear design.  Going through this process, I have more and more respect for the engineers that worked in the era before computer aided design and PLCs to take care of the timing and clearance issues.

Hopefully I won’t have to remake the gears, but it’s possible.  I love seeing things come together, but I suppose it’s the process that’s really enjoyable (and frustrating).  Like that video game I just had to beat when I was younger – as in a few month ago - you both love and hate these kinds of challenges.  I think I’ve got a decent design, and considering I just started my clock-making “career” a few weeks ago, it seems like things are off to a good start.

The next video deals with some of my thoughts before assembling the gears and planning how the escapement would work.  The second, and final, video is a time-lapse of my trusty Zen Toolworks CNC router cutting out the escapement gear.  The video didn’t turn out that well, so I give you permission to skip it if you’ve read this far.  I should also note that I was able to get the backplate onto my little Zen Toolworks 7×12 router to get the holes internally cut.  It was helpful to have the little clamps that I talk about here.

So a lot of information (and videos) in this one.  As for the gears, I might have had better luck using’s gear template generator.  I’ve actually got the PC version that can output DXFs, so not much of an excuse there!  Be sure to subscribe towards the upper-right of this page or follow via Twitter to see what comes next!

  1. Very interesting design Jeremy, I would be very interested in your final design and maybe look at your .dxf file if at all possible.
    Making clocks is very intriguing and using the cnc router helps in very quick prototyping.
    Keep up the good work

    • Thanks Bill! As for my final design, I honestly don’t know if I’ll ever get to that. I’ve moved on to some other projects.

      The router was definitely helpful in building this, and if you want the DXFs for this stage of the design, let me know, and I can try to dig them up.

      Thanks for reading!

      • Sorry to hear that you have moved on, but I know how frustrating it can be to stay on a project when you have other things you would like to accomplish.
        I would appreciate the DXF file and maybe I can help with some improvements. I do have a couple of gear generator programs that will help with the gear mesh problems and maybe some pin gears would do the trick.
        Thank you in advance for the DXF files and I’ll keep you informed it any breaking developments happen.


        • Bill,

          Sorry for the delayed response. I had the files stored in a weird location. Anyway, here’s the assembly drawing of everything. I think it’s the latest version. All the gears and back plate were made out of 1/4 inch plywood (probably a mistake there). I used Teflon washers as spacers, and I believe a 1/4 inch plastic (possibly Delrin) dowel as the axes.

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